Roll seal for vacuum strip-treating chamber



p 1969 c. E. KELLY ETAL 3,467,399

ROLL SEAL FOR VACUUM STRIP-TREATING CHAMBER Filed July 1'7, 196'? 4Sheets-Sheet 1 HVVE/VTORS CALI/IN E. KELLY and THOMAS E. N/CELY Alla/nayROLL SEAL FOR VACUUM STRIP-TREATING CHAMBER Filed July 17, 196'? Sept.16, 1969 c, E. KELLY ETAL 4 Sheets-Sheet 2 INVENTORS CALVIN E. KELLY andTHOMAS E. NICE LY By M A flarney P 1969 c, E. KELLY ETAL 3,467,399

ROLL SEAL FOR VACUUM STRIP-TREATING CHAMBER Filed July 17. 1967 4Sheets-Sheet :5

, P1Is= 3 7 //////////////////////A 22 /6 22 ,1 u l2- 1 I2 24 z 29 g 24V/////////////,/////// /////////[/,]//////Ld INVENTORS CALVIN E. KELLYand THOMAS E. N/CELY' Affarney Sept. 16, 1969 c. E. KELLY ETAL ROLL SEALFOR VACUUM STRIP-TREATING CHAMBER Filed July 17. 196'? 4 Sheets-Sheet 4TYPE-=5 T -i- INVENTORS CALVIN E. KELLY and THOMAS E. N/CELY AttorneyUnited States Patent US. Cl. 277-237 Claims ABSTRACT OF THE DISCLOSURE Aseal for strip entering a vacuum chamber including at least two rollsbetween and about which the strip passes. One of the rolls is fixed andthe other is bodily movable toward and from the fixed roll underadjustable spring pressure. Stops limit the movement of the movable rolltoward the fixed roll so that a gap is provided which is wider thanstrip thickness. The movable roll is journaled in bearings carried byhanger bars pivoted externally on the side walls of the box. Lowfriction sealing bars parallel to the rolls engage them peripherally.The rolls include a sponge rubber ring of special shape secured to eachend of the roll body, an end ring secured to each sponge rubber ring,and a low friction washer secured to the end ring and bearing againstthe side wall of the box to provide a dry vacuum seal.

This application which is a continuation-in-part of our co-pendingapplication Ser. No. 424,405, filed Jan. 8, 1965 and now abandoned,relates to seals for the entrance and exit of a vacuum strip-treatingchamber and, in particular, to a seal embodying a cluster of rolls whichafford a circuitous path for the strip and dry seal means slidablyengaging the peripheries and ends of the rolls.

It is desirable, in certain instances, to subject a traveling strip totreatment in a vacuum chamber. One example is the coating of steel stripwith aluminum, copper, or other metal by vapor deposition in a vacuum.Since the strip must be fed continuously into and withdrawn from thevacuum chamber, seals are required for the chamber entry and exit tomaintain the vacuum within the chamber while the strip enters and leavesit.

Seals for this general purpose have been previously provided such asshown in Minton Patent No. 1,595,240, Russell Patent No. 1,924,883 andNakaguchi Patent No. 3,048,992, but those seals of which we haveknowledge have various disadvantages. When a wet seal is used there isthe probability that the seal material will be sucked into the vacuumchamber, thus destroying the seal unless additional liquid is added. Theseal material can also cause damage to the strip, especially when it isfreshly coated. The seals generally depend upon both rolls bearingagainst the strip which will damage a fresh coating. It is advantageousto use undriven rolls to prevent damage to the coating on the strip.However, this requires that the rolls rotate with little friction.Former seals produced considerable friction, either because of metal tometal contact and/or because of axial forces produced on contactsurfaces as the rolls expand due to heat.

It is therefore an object of our invention to provide a vacuum seal fortraveling strip which eliminates damage to the strip.

Another object is to provide such a seal which has a controlled gapbetween adjacent rolls forming the seal.

Still another object is to provide such a seal which does not utilize aliquid sealing material.

A still further object is to provide such a seal which produces littlefriction between sealing surfaces.

3,467,399 Patented Sept. 16, 1969 These and other objects will be moreapparent after referring to the following specification and attacheddrawings in vwhich:

FIGURE 1 is a plan view, partly broken away and in horizontal section,of one multi-roll seal unit of our invention;

FIGURE 2 is a view taken on line IIII of FIGURE 1, partly broken awayand shown in section;

FIGURE 3 is a transverse section taken along the plane of line IIIIII ofFIGURE 2;

FIGURE 4 is a partial section taken along the plane of line.IVIV ofFIGURE 2;

FIGURE 5 is a view taken on the line VV of FIG- URE 1;

FIGURE 6 is a portion of FIGURE 3 enlarged;

FIGURE 7 is a view taken on line VIIVII of FIG- URE 3;

FIGURE 8 is a plan view of an outer vacuum chamber; and

FIGURE 9 is an elevation thereof.

Referring now in detail to the drawings, a preferred seal unit of ourinvention includes a roll-enclosing housing or box 10 comprising baseplates 11, side walls 12, end walls 13 and top plates 14. Accessopenings 15 in top plates 14 are closed by removable transparent coverplates 16. A fixed center roll 17 is journaled transversely 0f.box 10,in bearings 18 secured to side walls 12 by screws 19.

Adjacent its upper corners, box 10 has bearing pins 20, normal to sidewalls 12, secured thereto by screws 21. Rollhanger bars 22 are journaledon pins 20 by bearings 23. Bars 22 have bearings 24 at their lower endsin which are journaled the necks of rolls 25 and 26 which coact withroll 17 to form a sealing cluster within box 10. By virtue of hangerbars 22, rolls 25 and 26 may move toward and from roll 17. Side walls 12of box 10 have rollneck ports 27 permitting such movement. The hangerbars of each roll 25 and 26 are connected top and bottom by tie bars 22aand 22b, respectively. Ports 27a in the side walls permit movement ofthe latter.

As shown in FIGURE 3, the rolls 17, 25, and 26 extend the full width ofbox 10 and have seals 28 at their ends engaging the planed innersurfaces of side walls 12, which are highly polished to reduce frictionand give good sealing contact. FIGURE 6 shows a portion of one of theseals 28, which includes a steel ring 29 having a low friction washer 30of a high temperature synthetic resin such as Dixon Corporations Rulonresin chemically bonded thereto which is in wiping engagement with theinner surface of one of the side walls 12. A gasket ring 31 of hightemperature non-absorbing closed cell resilent material, such asCOHRLASTIC R10470 closed cell silicone sponge rubber which has aflexible temperature range of F. to 500 F. and which is manufactured bythe Connecticut Hard Rubber Company of New Haven, Conn, is disposedbetween end ring 29 and the end of roll body 32 and is secured to bothby means of high temperature cement. Thus, it is impossible foratmosphere to leak through or around the ring 31 from the outside. Theinner periphery of the gasket ring 31 is provided with equally spacedgrooves 31G so as to reduce the area of the sidewall of the ring andprovide a particular calculated pressure on the adjacent walls 12. Thisspecial design permits longitudinal thermal expansion of the seal rollswithout any substantial increase in pressure on the sidewalls andmaintains a positive seal without increase in drag.

Rolls 25 and 26 are urged toward roll 17 by adjustable spring assembly33 which is best shown in FIGURE 4. Lugs 34 extend laterally from plates12a attached to sidewalls 12 and are drilled and tapped to receiveadjusting screws 35 having a spring seat 36 at one end. A compressionspring 37 has one end on the seat of each bushing and a head 38 at theother. Heads 38 engage lugs 39 extending laterally from the lower endsof bars 22. Pin 39P, having a conical surface in contact with head 38maintains the force of spring 37 normal to bars 22. Stops 40, whichmaintain a pre-set minimum roll gap 42, limit angular movement of thebars thus effected by the spring 37. The gap between the rolls may beadjusted from outside the vacuum assembly by gap-adjusting assembly 43which in cludes a control shaft 44 supported by bushings 46 mounted insidewall 12 and extending laterally some distance from said sidewall. Aneccentric ring 48 secured to shaft 44 by key 50 is mounted in contactwith angle 52 welded to crossbar 22b. Shaft 44 is connected by means ofa flexible coupling 54 to shaft 56 which is mounted in the outer wall ofouter housing 58 by means of vacuum seal 60. Crank 62 affixed to theouter end of shaft 56 is used to control the gap. Suitable drive motorsand control'units (not shown) may be substituted for the crank 62.

Steel strip S is introduced into box through a slot 13a in the left handend wall 13, is trained around rolls 25, 17, and 26 as shown in FIGURE2, and is then brought out through a slot 13b in the right-hand end wall13. Guide troughs 64 are positioned partially around rolls 17, and 26 tofacilitate passage of the leading end of the strip around the rolls.Also to facilitate threading, eccentrics 48 are turned sufliciently toopen up spaces between rolls 25 and 26 and roll 17. These eccentrics 48are thereafter backed off to permit rolls 25 and 26 to provide anyselected small gaps between them and roll 17, under the pressure appliedby spring back-ups 33. The adjustment must be such that the strip is notsqueezed between the rolls.

Rolls 17, 25 and 26 have longitudinal sealing bars 66 which are made ofa temperature resistant material having a uniform texture substantiallysofter than, but not transferable to, the peripheral surface of theroll. Graphite is a suitable material. The inner surfaces of the bars 66do not need to precisely fit the roll contour initially since it wearsunder continued use until it does, and thus improves sealing efficiency.The sealing bars for rolls 25 and 26 are slidable in guide frames 68secured to end walls 13, and are provided with back-up springs 70 whichurge the bars 66 against the rolls. The guide frame for the sealing barengaging roll 17 is located in a central transverse wall 72 in the box10. This permits replacing or inspection of the bar seal from outside ofbox 10.

It will be evident that the combination of any two adjacent rolls of thethree, 17, 25 and 26, together with their sealing bars 66 and end seals28 and the roll-surface contact with the strip between the rolls,effectively closes off the flow of gas through the box 10 along thelength of the strip, except for the spaces between rolls, between theirends, and the edges of the strip. Thus, the strip passing between twoadjacent rolls is used to effect this seal. These spaces are quitesmall, however, and despite the leakage fiow therethrough, the twosealing barriers afforded by the three-roll assembly maintains a veryhigh pressure differential between the entrance and exit slots inopposite end walls. The roll-cluster sealing unit of the drawings may beduplicated in whole or in part (i.e, using only tworolls), to divide thetotal desired pressure differential among several units in series. Oneor the other type of unit is fitted tightly against the inlet or outletof a vacuum chamber (not shown).

It will be seen that the spring back-ups 33 always urge the rolls 25 and26 toward roll 17, but with a minimum gap greater than the thickness ofstrip S being established by stops so that the fresh coating materialwill not be damaged. The gaps are completely closed to effect minimumpump down time when seal modules are cold and not in operation. Whensufficient high vacuum is obtained and the coating process started, thecomponents within the seal module become hot and expand. The roll gapsare gradually opened until the equilibrium temperature is attainedwithin the module. Thus, minimum leakage is maintained permitting aminimum amount of pumping capacity. The gap can also be increased duringoperation by turning cranks 62. If irregular strip enters the spacebetween rolls, it will force the rolls apart against spring pressure,thus preventing damage to the strip. The gap will be closedinstantaneously as the irregular strip leaves the rolls. It will also benoted that the sealing bars always maintain intimate contact with therolls regardless of their positions.

Since the rolls 17, 25 and 26 are not driven, but are rotated solely bymovement of strip S, it is a necessity that very little friction beprovided by the seals 28. It is also imperative that there be norelative movement between rolls and strip. This is accomplished byeliminating all metal-to-metal contact during rotation of the rolls and-by providing as little axial force by resilient ring 31 as thedimensions of the rolls vary due to heat. This par ticular design ofseal unit is particularly well adapted for staging in series to effectan exit seal system for any degree of vacuum.

In ordinary use, it is desirable to enclose the rollcluster sealingmeans (one or more) in outer containment boxes 88 (FIGURES 8 and 9),having hinged doors 89 and 90, an exhaust outlet 91 and bellow-likeboots 92 adapted to mate with side walls 13, permitting ease ofinstallation without precision machining. Operation of a suitable vacuumpump connected to outlet 91 will serve to bring the pressure within box88 and outside box 10 to about 10- torrs and the pressure within box 10to 10 torrs. A gas-tight strip-treating chamber (not shown) to which therollcluster seals of our invention are secured, may therefore beoperated at this or even lower pressure since the limited amount of gasleakage through these seals may easily be removed by a pump ofreasonable capacity.

Although we have discovered herein the preferred embodiment of ourinvention, we intend to cover as well any change or modification thereinwhich may be made without departing from the spirit and scope of theinvention.

We claim:

1. A multiple-roll seal for traveling strip comprising a box having atop, a bottom and side and end walls;

a pair of bearings fixed on said side walls on a common ax1s;

a first rotatable roll journaled in said bearings and extendingsubstantially the full width of the box, said strip passing onlypartially around said roll;

a second pair of aligned bearings fixed in said side walls on a commonaxis spaced from but parallel to said first-mentioned axis;

hanger bars disposed externally of said box and journaled in thebearings of said second pair, respectively;

a third pair of aligned bearings carried, respectively, by

said bars;

a second rotatable roll extending substantially the full width of saidbox and having journals projecting through said side walls withclearance relative thereto, into the bearings of said third pair, saidstrip passing only partially around said second roll;

means urging said hanger bars and second roll toward said first roll;

the inner surfaces of said side walls adjacent the ends of said rollsbeing flat, the ends of said rolls having a low friction surface bearingagainst said inner surfaces;

said rolls including a main body portion, at least one end section, anda closed cell resilient ring member between said end section and saidbody portion;

first dry sealing means including a low friction sealing bar extendingparallel to said first roll for the full length thereof between theadjacent wall and the outer surface of the first roll where notcontacted by the strip, and resilient means urging the sealing baragainst the first roll; and

second dry sealing means including a second low friction sealing barextending parallel to said second roll for the full length thereofbetween the adjacent wall and the outer surface of the second roll wherenot contacted by the strip, and resilient means urging the secondsealing bar against the second roll;

said box having slits therein for the entrance and exit of the strip.

2. Apparatus according to claim 1 in which the low friction surface ofsaid roll includes a high temperature resin bonded to said end section.

3. Apparatus according to claim 1 in which said closed cell resilientring member is bonded to the end of said roll body and to said endsection, said resilient ring member being made of silicone spongerubber, the inner periphery of said resilient ring member havingtransverse grooves therein.

4. Apparatus according to claim 1 in which each of said sealing bars ismade of a temperature resistant material having a uniform texturesubstantially softer than, but not transferable to, the peripheral rollsurface, the inner surface of each bar being shaped to closely fit theassociated roll surface.

5. Apparatus according to claim 1 in which said means urging each ofsaid hanger bars is a spring, said apparatus including means outsidesaid box adjustably positioning said second roll closely adjacent thefirst roll, but with a minimum space between the rolls greater than thethickness of said strip, said last named means permitting movement ofsaid second roll away from said first roll.

6. Apparatus according to claim 2 in which said closed cell resilientring member is bonded to the end of said roll body and to said endsection, said resilient ring member being made of silicone spongerubber, the inner periphery of said resilient ring member havingtransverse grooves therein.

7. Apparatus according to claim 6 in which each of said sealing bars ismade of a temperature resistant material having a uniform texturesubstantially softer than the peripheral roll surface, the inner surfaceof each bar being shaped to closely fit the associated roll surface.

8. Apparatus according to claim 7 in which said means urging each ofsaid hanger bars is a spring, said apparatus including means outsidesaid box adjustably positioning said second roll closely adjacent thefirst roll, but with a minimum space between the rolls greater than thethickness of said strip, said last named means permitting movement ofsaid second roll away from said first roll.

9. Apparatus according to claim 3 in which each of said sealing bars ismade of a temperature resistant material having a uniform texturesubstantially softer than, but not transferable to, the peripheral rollsurface, the inner surface of said bar being shaped to closely fit theassociated roll surface.

10. Apparatus according to claim 9 in which said means urging each ofsaid hanger bars is a spring, said apparatus including means outsidesaid box adjustably positioning said second roll closely adjacent thefirst roll, but with a minimum space between the rolls greater than thethickness of said strip, said last named means permitting movement ofsaid second roll away from said first roll.

References Cited UNITED STATES PATENTS 1,595,240 8/1926 Minton.

1,683,254 9/ 1928 Minton.

1,924,883 8/1933 Russell.

2,721,144 10/ 1955 Penley.

3,048,992 8/ 1962 Nakaguchi. 3,158,507 11/1964 Alexander. 3,260,0007/7966 Schiffer.

FOREIGN PATENTS 1,267,775 6/1961 France.

LAVERNE D. GEIGER, Primary Examiner JEFFREY S. MEDNICK, AssistantExaminer Us. 01. X.R.

